Water and acid developable photoresist composition exhibiting improved adhesion

Abstract

A photopolymerizable composition suitable as a solder resist and capable of forming a resist film having characteristics in no way inferior to those of the conventional heat-curable type or organic solvent developed type solder resist, with the use of water or a dilute aqueous solution which is completely innocuous and higher in safety than the aqueous alkaline solution, and a method for producing a cured coated film pattern using the photopolymerizable composition.

What is claimed is: 
     
       1. A photopolymerizable composition comprising: (a) an aromatic epoxy resin derivative having from about 0.3 to about 10 mols/kg of polymerizable unsaturated groups and from about 0.1 to about 3 mols/kg of non-protonic onium salt containing groups having the formula: ##STR7## wherein R 1  is hydrogen or a hydrocarbon group having 1 to 8 carbons optionally substituted with a hydroxy group, an alkoxy group, an ester group or a halogen group and w.sup.⊕ is selected from onium salt-containing groups having the formula: ##STR8## wherein Z is N or P, R 2 , R 3  and R 4  may be the same or different and are selected from organic groups containing 1 to 14 carbons and wherein R 2  and R 3  or R 2 , R 3  and R 4  together, respectively, may form a heterocyclic group together with a nitrogen atom, phosphorus atom or a sulfur atom;   (b) from about 0.1 to about 10 parts by weight per 100 parts by weight of component (a) of a photopolymerization initiator; and   (c) from 10 to about 60 parts by weight per 100 parts by weight of component (a) of finely-divided mica having a mean particle size of from about 1 to about 10 μm.   
     
     
       2. The composition claimed in claim 1, wherein the aromatic epoxy resin derivative has a weight average molecular weight of about 500 to about 5000. 
     
     
       3. The composition claimed in claim 1, wherein the aromatic epoxy resin derivative has the polymerizable unsaturated group content of 0.5 to 5 moles per kilogram of resin solids. 
     
     
       4. The composition claimed in claim 1, wherein the aromatic epoxy resin derivative has the nonprotonic onium salt containing group content of 0.3 to 2 moles per kilogram of resin solids. 
     
     
       5. A photopolymerizable composition consisting: (a) an aromatic epoxy resin derivative having from about 0.3 to about 10 mols/kg of polymerizable unsaturated groups and from about 0.1 to about 3 mols/kg of non-protonic onium salt containing groups having the formula: ##STR9## wherein R 1  is hydrogen or a hydrocarbon group having 1 to 8 carbons optionally substituted with s hydroxy group, an alkoxy group, an ester group or a halogen group and w.sup.⊕ is selected from onium salt-containing groups having the formula: ##STR10## wherein Z is N or P, R 2 , R 3  and R 4  may be the same or different and are selected from organic groups containing 1 to 14 carbons and wherein R 2  and R 3  or R 2 , R 3  and R 4  together, respectively, may form a heterocyclic group together with a nitrogen atom, phosphorus atom or a sulfur atom;   (b) from about 0.1 to about 10 parts by weight per 100 parts by weight of component (a) of a photopolymerization initiators and   (c) from about 1 to about 15 parts by weight per 100 parts by weight or component (a) of a mono-functional polymerizable unsaturated monomer having the formula: ##STR11## wherein R 5  is hydrogen or methyl, R 6  is an alkylene group having 1 to 12 carbons, R 7  is an alkyl group having 1 to 4 carbons, R 8  is an alkyl group having 5 to 12 carbons and n is an integer of 0 to 3, inclusive.   
     
     
       6. A photopolymerizable composition as defined in claim 5, wherein component (a) has a weight average molecular weight of from about 500 to about 5,000. 
     
     
       7. A photopolymerizable composition as defined in claim 5, wherein component (a) has a polymerizable unsaturated group content of from about 0.5 to about 5 mols/kg of resin solids. 
     
     
       8. A photopolymerizable composition as defined in claim 5, wherein component (a) has a non-protonic onium salt containing group content of from about 0.3 to about 2 mols/kg of resin solids. 
     
     
       9. A photopolymerizable composition as defined in claim 5, further including a solvent. 
     
     
       10. A photopolymerizable composition as defined in claim 5, further including from about 0.1 to about 10 parts by weight based on 100 parts by eight of component (a) of a thermal curing catalyst. 
     
     
       11. A photopolymerizable composition as defined in claim 5, further including at least one additive selected from the group consisting or colored pigments, extenders, rust-proofing pigments, dyestuffs, levelling agents, deforming agents and run-proofing agents. 
     
     
       12. A photopolymerizable composition as defined in claim 5, wherein said means-functional polymerizable unsaturated monomer component (c) is an alkyl-substituted phenoxy-alkyl acrylate or an alkyl-substituted phenoxy-alkyl methacrylate. 
     
     
       13. A photopolymerizable composition as defined in claim 5, wherein component (c) is selected from hexylphenoxyhexyl methacrylate or c 1  -c 4  alkyl branched octylphenoxyhexyl methacrylate. 
     
     
       14. A method for producing a cured coating film pattern comprising the steps of preparing a photopolymerizable composition as defined in claim 1 or 5, coating the photopolymerizable composition on a substrate to form a coating film on the substrate, drying the coating film, exposing said coating film to light via a photomask having a desired circuit pattern, rinsing the coating film with water for removing an unexposed portion and subjecting the coating film carrying the circuit pattern to heating.